Gel materials use characteristics such as water absorbency and oil absorbency, and are used as water absorbing solvent or oil absorbing solvent that remove water or oil from a liquid or gas. Furthermore, after introducing an ion exchange group and a chelate group to gel materials, gel materials are also used as selective functional absorbing material.
For example, in Patent Document 1, a method is disclosed that fixes ion exchange particles in hydrogel. Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2003-514658